Merge branch 'master' into hemantvsn_SpringBootNonWebApp_30May18

.gitignore

@@ -34,8 +34,6 @@ spring-security-openid/src/main/resources/application.properties
 
 spring-all/*.log
 
-*.jar
-
 SpringDataInjectionDemo/.mvn/wrapper/maven-wrapper.properties
 
 spring-call-getters-using-reflection/.mvn/wrapper/maven-wrapper.properties

.travis.yml

@@ -4,7 +4,7 @@ before_install:
   - echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc
 
 install: skip
-script: travis_wait 60 mvn -q test -fae
+script: travis_wait 60 mvn -q install
 
 sudo: required
 

JGit/pom.xml

@@ -13,11 +13,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <maven.compiler.source>1.8</maven.compiler.source>
-        <maven.compiler.target>1.8</maven.compiler.target>
-    </properties>
     <repositories>
         <repository>
             <id>jgit-repository</id>
@@ -30,22 +25,28 @@
         <dependency>
             <groupId>org.eclipse.jgit</groupId>
             <artifactId>org.eclipse.jgit</artifactId>
-      <version>4.5.0.201609210915-r</version>
+            <version>${org.eclipse.jgit.version}</version>
         </dependency>
         <dependency>
             <groupId>org.eclipse.jgit</groupId>
             <artifactId>org.eclipse.jgit.archive</artifactId>
-      <version>4.5.0.201609210915-r</version>
+            <version>${org.eclipse.jgit.version}</version>
         </dependency>
         <dependency>
             <groupId>commons-io</groupId>
             <artifactId>commons-io</artifactId>
-		<version>2.5</version>
+            <version>${commons-io.version}</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>
-		<version>1.7.21</version>
+            <version>${org.slf4j.version}</version>
         </dependency>
     </dependencies>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <org.eclipse.jgit.version>4.5.0.201609210915-r</org.eclipse.jgit.version>
+    </properties>
+
 </project>

README.md

@@ -17,6 +17,10 @@ This project is **a collection of small and focused tutorials** each covering a
 Most of the tutorial projects are focused on the `Spring Framework` (and `Spring Security`).  
 In additional to Spring, the following technologies are in focus: `core Java`, `Jackson`, `HttpClient`, `Guava`. 
 
+Building the project
+====================
+To do the full build, do: `mvn install -Dgib.enabled=false`
+
 
 Working with the code in Eclipse
 ================================
@@ -29,3 +33,12 @@ Any IDE can be used to work with the projects, but if you're using Eclipse, cons
 CI - Jenkins
 ================================
 This tutorials project is being built **[>> HERE](https://rest-security.ci.cloudbees.com/job/tutorials-unit/)**
+
+### Relevant Articles: 
+================================
+
+- [Apache Maven Standard Directory Layout](http://www.baeldung.com/maven-directory-structure)
+- [Apache Maven Tutorial](http://www.baeldung.com/maven)
+- [Designing a User Friendly Java Library](http://www.baeldung.com/design-a-user-friendly-java-library)
+- [Java Service Provider Interface](http://www.baeldung.com/java-spi)
+- [Java Streams vs Vavr Streams](http://www.baeldung.com/vavr-java-streams)

activejdbc/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Introduction to ActiveJDBC](http://www.baeldung.com/active-jdbc)

activejdbc/pom.xml

@@ -7,20 +7,52 @@
     <packaging>jar</packaging>
     <name>activejdbc</name>
     <url>http://maven.apache.org</url>
-  <properties>
+
-    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <parent>
-    <activejdbc.version>1.4.13</activejdbc.version>
+        <artifactId>parent-modules</artifactId>
-    <environments>development.test,development</environments>
+        <groupId>com.baeldung</groupId>
-  </properties>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.javalite</groupId>
+            <artifactId>activejdbc</artifactId>
+            <version>${activejdbc.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>opensymphony</groupId>
+                    <artifactId>oscache</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>${mysql.connector.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.6.0</version>
+                <version>${maven-compiler-plugin.version}</version>
                 <configuration>
-          <source>1.8</source>
+                    <source>${java.version}</source>
-          <target>1.8</target>
+                    <target>${java.version}</target>
                     <encoding>UTF-8</encoding>
                 </configuration>
             </plugin>
@@ -49,14 +81,14 @@
                     <dependency>
                         <groupId>mysql</groupId>
                         <artifactId>mysql-connector-java</artifactId>
-            <version>5.1.34</version>
+                        <version>${mysql.connector.version}</version>
                     </dependency>
                 </dependencies>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.18.1</version>
+                <version>${maven-surefire-plugin.version}</version>
                 <configuration>
                     <reportFormat>brief</reportFormat>
                     <trimStackTrace>true</trimStackTrace>
@@ -73,35 +105,7 @@
             </plugin>
         </plugins>
     </build>
-  <dependencies>
+
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.12</version>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.javalite</groupId>
-      <artifactId>activejdbc</artifactId>
-      <version>${activejdbc.version}</version>
-      <exclusions>
-        <exclusion>
-          <groupId>opensymphony</groupId>
-          <artifactId>oscache</artifactId>
-        </exclusion>
-      </exclusions>
-    </dependency>
-    <dependency>
-      <groupId>mysql</groupId>
-      <artifactId>mysql-connector-java</artifactId>
-      <version>5.1.34</version>
-    </dependency>
-    <dependency>
-      <groupId>org.slf4j</groupId>
-      <artifactId>slf4j-simple</artifactId>
-      <version>1.7.9</version>
-    </dependency>
-  </dependencies>
     <repositories>
         <repository>
             <id>snapshots1</id>
@@ -114,6 +118,7 @@
             </snapshots>
         </repository>
     </repositories>
+
     <pluginRepositories>
         <pluginRepository>
             <id>snapshots2</id>
@@ -126,4 +131,13 @@
             </snapshots>
         </pluginRepository>
     </pluginRepositories>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <activejdbc.version>1.4.13</activejdbc.version>
+        <environments>development.test,development</environments>
+        <org.slf4j.version>1.7.9</org.slf4j.version>
+        <mysql.connector.version>5.1.34</mysql.connector.version>
+    </properties>
+
 </project>

akka-streams/pom.xml

@@ -1,15 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>akka-streams</artifactId>
+    <name>akka-streams</name>
+
     <parent>
         <artifactId>parent-modules</artifactId>
         <groupId>com.baeldung</groupId>
         <version>1.0.0-SNAPSHOT</version>
     </parent>
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>akka-streams</artifactId>
-    <name>akka-streams</name>
 
     <dependencies>
         <dependency>
@@ -23,6 +23,7 @@
             <version>${akkastreams.version}</version>
         </dependency>
     </dependencies>
+
     <properties>
         <akkastreams.version>2.5.2</akkastreams.version>
     </properties>

algorithms/README.md

@@ -16,3 +16,9 @@
 - [Introduction to Minimax Algorithm](http://www.baeldung.com/java-minimax-algorithm)
 - [How to Calculate Levenshtein Distance in Java?](http://www.baeldung.com/java-levenshtein-distance)
 - [How to Find the Kth Largest Element in Java](http://www.baeldung.com/java-kth-largest-element)
+- [Multi-Swarm Optimization Algorithm in Java](http://www.baeldung.com/java-multi-swarm-algorithm)
+- [A Maze Solver in Java](http://www.baeldung.com/java-solve-maze)
+- [Create a Sudoku Solver in Java](http://www.baeldung.com/java-sudoku)
+- [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
+- [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
+- [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)

algorithms/pom.xml

@@ -5,12 +5,6 @@
     <artifactId>algorithms</artifactId>
     <version>0.0.1-SNAPSHOT</version>
 
-    <properties>
-        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
-        <lombok.version>1.16.12</lombok.version>
-        <commons-math3.version>3.6.1</commons-math3.version>
-    </properties>
-
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
@@ -32,17 +26,22 @@
         <dependency>
             <groupId>io.jenetics</groupId>
             <artifactId>jenetics</artifactId>
-            <version>3.7.0</version>
+            <version>${io.jenetics.version}</version>
         </dependency>
         <dependency>
             <groupId>org.jgrapht</groupId>
             <artifactId>jgrapht-core</artifactId>
-            <version>1.0.1</version>
+            <version>${org.jgrapht.core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>pl.allegro.finance</groupId>
+            <artifactId>tradukisto</artifactId>
+            <version>${tradukisto.version}</version>
         </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <version>3.9.0</version>
+            <version>${org.assertj.core.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -58,6 +57,7 @@
             </plugins>
         </pluginManagement>
     </build>
+
     <reporting>
         <plugins>
             <plugin>
@@ -77,4 +77,15 @@
             </plugin>
         </plugins>
     </reporting>
+
+    <properties>
+        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
+        <lombok.version>1.16.12</lombok.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <tradukisto.version>1.0.1</tradukisto.version>
+        <io.jenetics.version>3.7.0</io.jenetics.version>
+        <org.jgrapht.core.version>1.0.1</org.jgrapht.core.version>
+        <org.assertj.core.version>3.9.0</org.assertj.core.version>
+    </properties>
+
 </project>

algorithms/src/main/java/com/baeldung/algorithms/RunAlgorithm.java

@@ -6,6 +6,7 @@ import com.baeldung.algorithms.ga.annealing.SimulatedAnnealing;
 import com.baeldung.algorithms.ga.ant_colony.AntColonyOptimization;
 import com.baeldung.algorithms.ga.binary.SimpleGeneticAlgorithm;
 import com.baeldung.algorithms.slope_one.SlopeOne;
+import com.baeldung.algorithms.pairsaddupnumber.FindPairs;
 
 public class RunAlgorithm {
 
@@ -17,6 +18,7 @@ public class RunAlgorithm {
 		System.out.println("3 - Simple Genetic Algorithm");
 		System.out.println("4 - Ant Colony");
 		System.out.println("5 - Dijkstra");
+		System.out.println("6 - All pairs in an array that add up to a given sum");
 		int decision = in.nextInt();
 		switch (decision) {
 		case 1:
@@ -37,6 +39,12 @@ public class RunAlgorithm {
 		case 5:
 			System.out.println("Please run the DijkstraAlgorithmTest.");
 			break;
+		case 6:
+			final FindPairs findPairs = new FindPairs();
+			final int[] input = {1, 4, 3, 2, 1, 4, 4, 3, 3};
+			final int sum = 6;
+			findPairs.execute(input, sum);
+			break;
 		default:
 			System.out.println("Unknown option");
 			break;

algorithms/src/main/java/com/baeldung/algorithms/multiswarm/Constants.java

@@ -0,0 +1,47 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Constants used by the Multi-swarm optimization algorithms.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Constants {
+
+	/**
+	 * The inertia factor encourages a particle to continue moving in its
+	 * current direction.
+	 */
+	public static final double INERTIA_FACTOR = 0.729;
+
+	/**
+	 * The cognitive weight encourages a particle to move toward its historical
+	 * best-known position.
+	 */
+	public static final double COGNITIVE_WEIGHT = 1.49445;
+
+	/**
+	 * The social weight encourages a particle to move toward the best-known
+	 * position found by any of the particle’s swarm-mates.
+	 */
+	public static final double SOCIAL_WEIGHT = 1.49445;
+
+	/**
+	 * The global weight encourages a particle to move toward the best-known
+	 * position found by any particle in any swarm.
+	 */
+	public static final double GLOBAL_WEIGHT = 0.3645;
+
+	/**
+	 * Upper bound for the random generation. We use it to reduce the
+	 * computation time since we can rawly estimate it.
+	 */
+	public static final int PARTICLE_UPPER_BOUND = 10000000;
+
+	/**
+	 * Private constructor for utility class.
+	 */
+	private Constants() {
+	}
+
+}

algorithms/src/main/java/com/baeldung/algorithms/multiswarm/FitnessFunction.java

@@ -0,0 +1,21 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Interface for a fitness function, used to decouple the main algorithm logic
+ * from the specific problem solution.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public interface FitnessFunction {
+
+	/**
+	 * Returns the fitness of a particle given its position.
+	 * 
+	 * @param particlePosition
+	 *            the position of the particle
+	 * @return the fitness of the particle
+	 */
+	public double getFitness(long[] particlePosition);
+
+}

algorithms/src/main/java/com/baeldung/algorithms/multiswarm/Multiswarm.java

@@ -0,0 +1,227 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Represents a collection of {@link Swarm}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Multiswarm {
+
+	/**
+	 * The swarms managed by this multiswarm.
+	 */
+	private Swarm[] swarms;
+
+	/**
+	 * The best position found within all the {@link #swarms}.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness score found within all the {@link #swarms}.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * A random generator.
+	 */
+	private Random random = new Random();
+
+	/**
+	 * The fitness function used to determine how good is a particle.
+	 */
+	private FitnessFunction fitnessFunction;
+
+	/**
+	 * Instantiates a new Multiswarm.
+	 * 
+	 * @param numSwarms
+	 *            the number of {@link #swarms}
+	 * @param particlesPerSwarm
+	 *            the number of particle for each {@link #swarms}
+	 * @param fitnessFunction
+	 *            the {@link #fitnessFunction}
+	 */
+	public Multiswarm(int numSwarms, int particlesPerSwarm, FitnessFunction fitnessFunction) {
+		this.fitnessFunction = fitnessFunction;
+		this.swarms = new Swarm[numSwarms];
+		for (int i = 0; i < numSwarms; i++) {
+			swarms[i] = new Swarm(particlesPerSwarm);
+		}
+	}
+
+	/**
+	 * Main loop of the algorithm. Iterates all particles of all
+	 * {@link #swarms}. For each particle, computes the new fitness and checks
+	 * if a new best position has been found among itself, the swarm and all the
+	 * swarms and finally updates the particle position and speed.
+	 */
+	public void mainLoop() {
+		for (Swarm swarm : swarms) {
+			for (Particle particle : swarm.getParticles()) {
+
+				long[] particleOldPosition = particle.getPosition().clone();
+
+				// Calculate the particle fitness.
+				particle.setFitness(fitnessFunction.getFitness(particleOldPosition));
+
+				// Check if a new best position has been found for the particle
+				// itself, within the swarm and the multiswarm.
+				if (particle.getFitness() > particle.getBestFitness()) {
+					particle.setBestFitness(particle.getFitness());
+					particle.setBestPosition(particleOldPosition);
+
+					if (particle.getFitness() > swarm.getBestFitness()) {
+						swarm.setBestFitness(particle.getFitness());
+						swarm.setBestPosition(particleOldPosition);
+
+						if (swarm.getBestFitness() > bestFitness) {
+							bestFitness = swarm.getBestFitness();
+							bestPosition = swarm.getBestPosition().clone();
+						}
+
+					}
+				}
+
+				// Updates the particle position by adding the speed to the
+				// actual position.
+				long[] position = particle.getPosition();
+				long[] speed = particle.getSpeed();
+
+				position[0] += speed[0];
+				position[1] += speed[1];
+
+				// Updates the particle speed.
+				speed[0] = getNewParticleSpeedForIndex(particle, swarm, 0);
+				speed[1] = getNewParticleSpeedForIndex(particle, swarm, 1);
+			}
+		}
+	}
+
+	/**
+	 * Computes a new speed for a given particle of a given swarm on a given
+	 * axis. The new speed is computed using the formula:
+	 * 
+	 * <pre>
+	 * ({@link Constants#INERTIA_FACTOR} * {@link Particle#getSpeed()}) + 
+	 * (({@link Constants#COGNITIVE_WEIGHT} * random(0,1)) * ({@link Particle#getBestPosition()} - {@link Particle#getPosition()})) +
+	 * (({@link Constants#SOCIAL_WEIGHT} * random(0,1)) * ({@link Swarm#getBestPosition()} - {@link Particle#getPosition()})) + 
+	 * (({@link Constants#GLOBAL_WEIGHT} * random(0,1)) * ({@link #bestPosition} - {@link Particle#getPosition()}))
+	 * </pre>
+	 *
+	 * @param particle
+	 *            the particle whose new speed needs to be computed
+	 * @param swarm
+	 *            the swarm which contains the particle
+	 * @param index
+	 *            the index of the particle axis whose speeds needs to be
+	 *            computed
+	 * @return the new speed of the particle passed on the given axis
+	 */
+	private int getNewParticleSpeedForIndex(Particle particle, Swarm swarm, int index) {
+		return (int) ((Constants.INERTIA_FACTOR * particle.getSpeed()[index])
+				+ (randomizePercentage(Constants.COGNITIVE_WEIGHT)
+						* (particle.getBestPosition()[index] - particle.getPosition()[index]))
+				+ (randomizePercentage(Constants.SOCIAL_WEIGHT)
+						* (swarm.getBestPosition()[index] - particle.getPosition()[index]))
+				+ (randomizePercentage(Constants.GLOBAL_WEIGHT)
+						* (bestPosition[index] - particle.getPosition()[index])));
+	}
+
+	/**
+	 * Returns a random number between 0 and the value passed as argument.
+	 *
+	 * @param value
+	 *            the value to randomize
+	 * @return a random value between 0 and the one passed as argument
+	 */
+	private double randomizePercentage(double value) {
+		return random.nextDouble() * value;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		result = prime * result + ((fitnessFunction == null) ? 0 : fitnessFunction.hashCode());
+		result = prime * result + ((random == null) ? 0 : random.hashCode());
+		result = prime * result + Arrays.hashCode(swarms);
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Multiswarm other = (Multiswarm) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (fitnessFunction == null) {
+			if (other.fitnessFunction != null)
+				return false;
+		} else if (!fitnessFunction.equals(other.fitnessFunction))
+			return false;
+		if (random == null) {
+			if (other.random != null)
+				return false;
+		} else if (!random.equals(other.random))
+			return false;
+		if (!Arrays.equals(swarms, other.swarms))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Multiswarm [swarms=" + Arrays.toString(swarms) + ", bestPosition=" + Arrays.toString(bestPosition)
+				+ ", bestFitness=" + bestFitness + ", random=" + random + ", fitnessFunction=" + fitnessFunction + "]";
+	}
+
+}

algorithms/src/main/java/com/baeldung/algorithms/multiswarm/Particle.java

@@ -0,0 +1,204 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+
+/**
+ * Represents a particle, the basic component of a {@link Swarm}.
+ * 
+ * @author Donato Rimenti
+ * 
+ */
+public class Particle {
+
+	/**
+	 * The current position of this particle.
+	 */
+	private long[] position;
+
+	/**
+	 * The speed of this particle.
+	 */
+	private long[] speed;
+
+	/**
+	 * The fitness of this particle for the current position.
+	 */
+	private double fitness;
+
+	/**
+	 * The best position found by this particle.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness found by this particle.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * Instantiates a new Particle.
+	 *
+	 * @param initialPosition
+	 *            the initial {@link #position}
+	 * @param initialSpeed
+	 *            the initial {@link #speed}
+	 */
+	public Particle(long[] initialPosition, long[] initialSpeed) {
+		this.position = initialPosition;
+		this.speed = initialSpeed;
+	}
+
+	/**
+	 * Gets the {@link #position}.
+	 *
+	 * @return the {@link #position}
+	 */
+	public long[] getPosition() {
+		return position;
+	}
+
+	/**
+	 * Gets the {@link #speed}.
+	 *
+	 * @return the {@link #speed}
+	 */
+	public long[] getSpeed() {
+		return speed;
+	}
+
+	/**
+	 * Gets the {@link #fitness}.
+	 *
+	 * @return the {@link #fitness}
+	 */
+	public double getFitness() {
+		return fitness;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/**
+	 * Sets the {@link #position}.
+	 *
+	 * @param position
+	 *            the new {@link #position}
+	 */
+	public void setPosition(long[] position) {
+		this.position = position;
+	}
+
+	/**
+	 * Sets the {@link #speed}.
+	 *
+	 * @param speed
+	 *            the new {@link #speed}
+	 */
+	public void setSpeed(long[] speed) {
+		this.speed = speed;
+	}
+
+	/**
+	 * Sets the {@link #fitness}.
+	 *
+	 * @param fitness
+	 *            the new {@link #fitness}
+	 */
+	public void setFitness(double fitness) {
+		this.fitness = fitness;
+	}
+
+	/**
+	 * Sets the {@link #bestPosition}.
+	 *
+	 * @param bestPosition
+	 *            the new {@link #bestPosition}
+	 */
+	public void setBestPosition(long[] bestPosition) {
+		this.bestPosition = bestPosition;
+	}
+
+	/**
+	 * Sets the {@link #bestFitness}.
+	 *
+	 * @param bestFitness
+	 *            the new {@link #bestFitness}
+	 */
+	public void setBestFitness(double bestFitness) {
+		this.bestFitness = bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		temp = Double.doubleToLongBits(fitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(position);
+		result = prime * result + Arrays.hashCode(speed);
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Particle other = (Particle) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (Double.doubleToLongBits(fitness) != Double.doubleToLongBits(other.fitness))
+			return false;
+		if (!Arrays.equals(position, other.position))
+			return false;
+		if (!Arrays.equals(speed, other.speed))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Particle [position=" + Arrays.toString(position) + ", speed=" + Arrays.toString(speed) + ", fitness="
+				+ fitness + ", bestPosition=" + Arrays.toString(bestPosition) + ", bestFitness=" + bestFitness + "]";
+	}
+
+}

algorithms/src/main/java/com/baeldung/algorithms/multiswarm/Swarm.java

@@ -0,0 +1,155 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Represents a collection of {@link Particle}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Swarm {
+
+	/**
+	 * The particles of this swarm.
+	 */
+	private Particle[] particles;
+
+	/**
+	 * The best position found within the particles of this swarm.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness score found within the particles of this swarm.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * A random generator.
+	 */
+	private Random random = new Random();
+
+	/**
+	 * Instantiates a new Swarm.
+	 *
+	 * @param numParticles
+	 *            the number of particles of the swarm
+	 */
+	public Swarm(int numParticles) {
+		particles = new Particle[numParticles];
+		for (int i = 0; i < numParticles; i++) {
+			long[] initialParticlePosition = { random.nextInt(Constants.PARTICLE_UPPER_BOUND),
+					random.nextInt(Constants.PARTICLE_UPPER_BOUND) };
+			long[] initialParticleSpeed = { random.nextInt(Constants.PARTICLE_UPPER_BOUND),
+					random.nextInt(Constants.PARTICLE_UPPER_BOUND) };
+			particles[i] = new Particle(initialParticlePosition, initialParticleSpeed);
+		}
+	}
+
+	/**
+	 * Gets the {@link #particles}.
+	 *
+	 * @return the {@link #particles}
+	 */
+	public Particle[] getParticles() {
+		return particles;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/**
+	 * Sets the {@link #bestPosition}.
+	 *
+	 * @param bestPosition
+	 *            the new {@link #bestPosition}
+	 */
+	public void setBestPosition(long[] bestPosition) {
+		this.bestPosition = bestPosition;
+	}
+
+	/**
+	 * Sets the {@link #bestFitness}.
+	 *
+	 * @param bestFitness
+	 *            the new {@link #bestFitness}
+	 */
+	public void setBestFitness(double bestFitness) {
+		this.bestFitness = bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		result = prime * result + Arrays.hashCode(particles);
+		result = prime * result + ((random == null) ? 0 : random.hashCode());
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Swarm other = (Swarm) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (!Arrays.equals(particles, other.particles))
+			return false;
+		if (random == null) {
+			if (other.random != null)
+				return false;
+		} else if (!random.equals(other.random))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Swarm [particles=" + Arrays.toString(particles) + ", bestPosition=" + Arrays.toString(bestPosition)
+				+ ", bestFitness=" + bestFitness + ", random=" + random + "]";
+	}
+
+}

algorithms/src/main/java/com/baeldung/algorithms/numberwordconverter/NumberWordConverter.java

@@ -0,0 +1,75 @@
+package com.baeldung.algorithms.numberwordconverter;
+
+import java.math.BigDecimal;
+
+import pl.allegro.finance.tradukisto.MoneyConverters;
+
+public class NumberWordConverter {
+
+    public static final String INVALID_INPUT_GIVEN = "Invalid input given";
+
+    public static final String[] ones = { "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
+
+    public static final String[] tens = {
+      "", // 0
+      "", // 1
+      "twenty", // 2
+      "thirty", // 3
+      "forty", // 4
+      "fifty", // 5
+      "sixty", // 6
+      "seventy", // 7
+      "eighty", // 8
+      "ninety" // 9
+    };
+
+    public static String getMoneyIntoWords(String input) {
+        MoneyConverters converter = MoneyConverters.ENGLISH_BANKING_MONEY_VALUE;
+        return converter.asWords(new BigDecimal(input));
+    }
+
+    public static String getMoneyIntoWords(final double money) {
+        long dollar = (long) money;
+        long cents = Math.round((money - dollar) * 100);
+        if (money == 0D) {
+            return "";
+        }
+        if (money < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        String dollarPart = "";
+        if (dollar > 0) {
+            dollarPart = convert(dollar) + " dollar" + (dollar == 1 ? "" : "s");
+        }
+        String centsPart = "";
+        if (cents > 0) {
+            if (dollarPart.length() > 0) {
+                centsPart = " and ";
+            }
+            centsPart += convert(cents) + " cent" + (cents == 1 ? "" : "s");
+        }
+        return dollarPart + centsPart;
+    }
+
+    private static String convert(final long n) {
+        if (n < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        if (n < 20) {
+            return ones[(int) n];
+        }
+        if (n < 100) {
+            return tens[(int) n / 10] + ((n % 10 != 0) ? " " : "") + ones[(int) n % 10];
+        }
+        if (n < 1000) {
+            return ones[(int) n / 100] + " hundred" + ((n % 100 != 0) ? " " : "") + convert(n % 100);
+        }
+        if (n < 1_000_000) {
+            return convert(n / 1000) + " thousand" + ((n % 1000 != 0) ? " " : "") + convert(n % 1000);
+        }
+        if (n < 1_000_000_000) {
+            return convert(n / 1_000_000) + " million" + ((n % 1_000_000 != 0) ? " " : "") + convert(n % 1_000_000);
+        }
+        return convert(n / 1_000_000_000) + " billion" + ((n % 1_000_000_000 != 0) ? " " : "") + convert(n % 1_000_000_000);
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/DifferentPairs.java

@@ -0,0 +1,72 @@
+package com.baeldung.algorithms.pairsaddupnumber;
+
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.IntStream;
+
+/**
+ * Find all different pairs of numbers in an array that add up to a given sum - Complexity O(n)
+ */
+public class DifferentPairs {
+
+    /**
+     * Show all different pairs using traditional "for" loop
+     *
+     * @param input - number's array
+     * @param sum   - given sum
+     * @return - number's array with all existing pairs. This list will contain just one pair's element because
+     * the other one can be calculated with SUM - element_1 = element_2
+     */
+    public static List<Integer> findPairsWithForLoop(int[] input, int sum) {
+        final List<Integer> allDifferentPairs = new ArrayList<>();
+        // Aux. hash map
+        final Map<Integer, Integer> pairs = new HashMap();
+        for (int i : input) {
+            if (pairs.containsKey(i)) {
+                if (pairs.get(i) != null) {
+                    // Add pair to returned list
+                    allDifferentPairs.add(i);
+                }
+                // Mark pair as added to prevent duplicates
+                pairs.put(sum - i, null);
+            } else if (!pairs.containsValue(i)) {
+                // Add pair to aux. hash map
+                pairs.put(sum - i, i);
+            }
+        }
+        return allDifferentPairs;
+    }
+
+    /**
+     * Show all different pairs using Java 8 stream API
+     *
+     * @param input - number's array
+     * @param sum   - given sum
+     * @return - number's array with all existing pairs. This list will contain just one pair's element because
+     * the other one can be calculated with SUM - element_1 = element_2
+     */
+    public static List<Integer> findPairsWithStreamApi(int[] input, int sum) {
+        final List<Integer> allDifferentPairs = new ArrayList<>();
+        // Aux. hash map
+        final Map<Integer, Integer> pairs = new HashMap();
+        IntStream.range(0, input.length).forEach(i -> {
+                    if (pairs.containsKey(input[i])) {
+                        if (pairs.get(input[i]) != null) {
+                            // Add pair to returned list
+                            allDifferentPairs.add(input[i]);
+                        }
+                        // Mark pair as added to prevent duplicates
+                        pairs.put(sum - input[i], null);
+                    } else if (!pairs.containsValue(input[i])) {
+                        // Add pair to aux. hash map
+                        pairs.put(sum - input[i], input[i]);
+                    }
+                }
+        );
+        return allDifferentPairs;
+    }
+}
+

algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/ExistingPairs.java

@@ -0,0 +1,51 @@
+package com.baeldung.algorithms.pairsaddupnumber;
+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.IntStream;
+
+/**
+ * Find all existing pairs of numbers in an array that add up to a given sum - Complexity O(n^2) "Brute force"
+ */
+public class ExistingPairs {
+
+    /**
+     * Show all existing pairs using traditional "for" loop
+     *
+     * @param input - number's array
+     * @param sum   - given sum
+     * @return - number's array with all existing pairs. This list will contain just one pair's element because
+     * the other one can be calculated with SUM - element_1 = element_2
+     */
+    public static List<Integer> findPairsWithForLoop(int[] input, int sum) {
+        final List<Integer> allExistingPairs = new ArrayList<>();
+        for (int i = 0; i < input.length; i++) {
+            for (int j = 0; j < input.length; j++) {
+                if (j != i && (input[i] + input[j]) == sum) {
+                    allExistingPairs.add(input[i]);
+                }
+            }
+        }
+        return allExistingPairs;
+    }
+
+    /**
+     * Show all existing pairs using Java 8 stream API
+     *
+     * @param input - number's array
+     * @param sum   - given sum
+     * @return - number's array with all existing pairs. This list will contain just one pair's element because
+     * the other one can be calculated with SUM - element_1 = element_2
+     */
+    public static List<Integer> findPairsWithStreamApi(int[] input, int sum) {
+        final List<Integer> allExistingPairs = new ArrayList<>();
+        IntStream.range(0, input.length).forEach(i ->
+                IntStream.range(0, input.length)
+                        .filter(j -> i != j && input[i] + input[j] == sum)
+                        .forEach(j -> allExistingPairs.add(input[i]))
+        );
+        return allExistingPairs;
+    }
+}
+

algorithms/src/main/java/com/baeldung/algorithms/pairsaddupnumber/FindPairs.java

@@ -0,0 +1,74 @@
+package com.baeldung.algorithms.pairsaddupnumber;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.IntStream;
+
+
+public class FindPairs {
+
+    public void execute(int[] input, int sum) {
+        final StringBuilder inputArray = new StringBuilder();
+        inputArray.append("{");
+        IntStream.range(0, input.length).forEach(i -> inputArray.append(input[i] + ", "));
+        inputArray.append("}");
+        System.out.println(" Given number array: " + inputArray.toString());
+        System.out.println(" Given sum: " + sum);
+        /* Call services */
+        getDifferentPairs(input, sum);
+        getExistingPairs(input, sum);
+    }
+
+    /**
+     * Print all existing pairs for the given inputs: input array & sum number
+     */
+    private static void getExistingPairs(int[] input, int sum) {
+        List<Integer> pairs = new ArrayList<>();
+        System.out.println("~ All existing pairs ~");
+
+        /* Traditional FOR loop */
+        // Call method
+        pairs = ExistingPairs.findPairsWithForLoop(input, sum);
+        // Create a pretty printing
+        final StringBuilder output1 = new StringBuilder();
+        pairs.forEach((pair) -> output1.append("{" + pair + ", " + (sum - pair) + "}, "));
+        // Print result
+        System.out.println("Traditional \"for\" loop: " + output1.toString().substring(0, output1.length() - 2));
+
+        /* Java 8 stream API */
+        // Call the method
+        pairs = ExistingPairs.findPairsWithStreamApi(input, sum);
+        // Create a pretty printing
+        final StringBuilder output2 = new StringBuilder();
+        pairs.forEach((pair) -> output2.append("{" + pair + ", " + (sum - pair) + "}, "));
+        // Print result
+        System.out.println("Java 8 streams API: " + output2.toString().substring(0, output2.length() - 2));
+    }
+
+    /**
+     * Print all different pairs for the given inputs: input array & sum number
+     */
+    private static void getDifferentPairs(int[] input, int sum) {
+        List<Integer> pairs = new ArrayList<>();
+        System.out.println("~ All different pairs ~");
+
+        /* Traditional FOR loop */
+        // Call method
+        pairs = DifferentPairs.findPairsWithForLoop(input, sum);
+        // Create a pretty printing
+        final StringBuilder output3 = new StringBuilder();
+        pairs.forEach((pair) -> output3.append("{" + pair + ", " + (sum - pair) + "}, "));
+        // Print result
+        System.out.println("Traditional \"for\" loop: " + output3.toString().substring(0, output3.length() - 2));
+
+        /* Java 8 stream API */
+        // Call method
+        pairs = DifferentPairs.findPairsWithStreamApi(input, sum);
+        // Create a pretty printing
+        final StringBuilder output4 = new StringBuilder();
+        pairs.forEach((pair) -> output4.append("{" + pair + ", " + (sum - pair) + "}, "));
+        // Print result
+        System.out.println("Java 8 streams API: " + output4.toString().substring(0, output4.length() - 2));
+    }
+}
+

algorithms/src/main/java/com/baeldung/algorithms/sudoku/BacktrackingAlgorithm.java

@@ -40,15 +40,15 @@ public class BacktrackingAlgorithm {
     }
 
     private boolean solve(int[][] board) {
-        for (int r = BOARD_START_INDEX; r < BOARD_SIZE; r++) {
+        for (int row = BOARD_START_INDEX; row < BOARD_SIZE; row++) {
-            for (int c = BOARD_START_INDEX; c < BOARD_SIZE; c++) {
+            for (int column = BOARD_START_INDEX; column < BOARD_SIZE; column++) {
-                if (board[r][c] == NO_VALUE) {
+                if (board[row][column] == NO_VALUE) {
                     for (int k = MIN_VALUE; k <= MAX_VALUE; k++) {
-                        board[r][c] = k;
+                        board[row][column] = k;
-                        if (isValid(board, r, c) && solve(board)) {
+                        if (isValid(board, row, column) && solve(board)) {
                             return true;
                         }
-                        board[r][c] = NO_VALUE;
+                        board[row][column] = NO_VALUE;
                     }
                     return false;
                 }
@@ -57,44 +57,44 @@ public class BacktrackingAlgorithm {
         return true;
     }
 
-    private boolean isValid(int[][] board, int r, int c) {
+    private boolean isValid(int[][] board, int row, int column) {
-        return rowConstraint(board, r) &&
+        return rowConstraint(board, row) &&
-          columnConstraint(board, c) &&
+          columnConstraint(board, column) &&
-          subsectionConstraint(board, r, c);
+          subsectionConstraint(board, row, column);
     }
 
-    private boolean subsectionConstraint(int[][] board, int r, int c) {
+    private boolean subsectionConstraint(int[][] board, int row, int column) {
         boolean[] constraint = new boolean[BOARD_SIZE];
-        int subsectionRowStart = (r / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionRowStart = (row / SUBSECTION_SIZE) * SUBSECTION_SIZE;
         int subsectionRowEnd = subsectionRowStart + SUBSECTION_SIZE;
 
-        int subsectionColumnStart = (c / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionColumnStart = (column / SUBSECTION_SIZE) * SUBSECTION_SIZE;
         int subsectionColumnEnd = subsectionColumnStart + SUBSECTION_SIZE;
 
-        for (int i = subsectionRowStart; i < subsectionRowEnd; i++) {
+        for (int r = subsectionRowStart; r < subsectionRowEnd; r++) {
-            for (int j = subsectionColumnStart; j < subsectionColumnEnd; j++) {
+            for (int c = subsectionColumnStart; c < subsectionColumnEnd; c++) {
-                if (!checkConstraint(board, i, constraint, j)) return false;
+                if (!checkConstraint(board, r, constraint, c)) return false;
             }
         }
         return true;
     }
 
-    private boolean columnConstraint(int[][] board, int c) {
+    private boolean columnConstraint(int[][] board, int column) {
         boolean[] constraint = new boolean[BOARD_SIZE];
         return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, i, constraint, c));
+          .allMatch(row -> checkConstraint(board, row, constraint, column));
     }
 
-    private boolean rowConstraint(int[][] board, int r) {
+    private boolean rowConstraint(int[][] board, int row) {
         boolean[] constraint = new boolean[BOARD_SIZE];
         return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, r, constraint, i));
+          .allMatch(column -> checkConstraint(board, row, constraint, column));
     }
 
-    private boolean checkConstraint(int[][] board, int r, boolean[] constraint, int c) {
+    private boolean checkConstraint(int[][] board, int row, boolean[] constraint, int column) {
-        if (board[r][c] != NO_VALUE) {
+        if (board[row][column] != NO_VALUE) {
-            if (!constraint[board[r][c] - 1]) {
+            if (!constraint[board[row][column] - 1]) {
-                constraint[board[r][c] - 1] = true;
+                constraint[board[row][column] - 1] = true;
             } else {
                 return false;
             }

algorithms/src/main/java/com/baeldung/algorithms/sudoku/DancingLinksAlgorithm.java

@@ -34,8 +34,8 @@ public class DancingLinksAlgorithm {
         dlx.runSolver();
     }
 
-    private int getIndex(int row, int col, int num) {
+    private int getIndex(int row, int column, int num) {
-        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (col - 1) * BOARD_SIZE + (num - 1);
+        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (column - 1) * BOARD_SIZE + (num - 1);
     }
 
     private boolean[][] createExactCoverBoard() {
@@ -51,12 +51,12 @@ public class DancingLinksAlgorithm {
     }
 
     private int checkSubsectionConstraint(boolean[][] coverBoard, int hBase) {
-        for (int br = COVER_START_INDEX; br <= BOARD_SIZE; br += SUBSECTION_SIZE) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row += SUBSECTION_SIZE) {
-            for (int bc = COVER_START_INDEX; bc <= BOARD_SIZE; bc += SUBSECTION_SIZE) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column += SUBSECTION_SIZE) {
                 for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                    for (int rDelta = 0; rDelta < SUBSECTION_SIZE; rDelta++) {
+                    for (int rowDelta = 0; rowDelta < SUBSECTION_SIZE; rowDelta++) {
-                        for (int cDelta = 0; cDelta < SUBSECTION_SIZE; cDelta++) {
+                        for (int columnDelta = 0; columnDelta < SUBSECTION_SIZE; columnDelta++) {
-                            int index = getIndex(br + rDelta, bc + cDelta, n);
+                            int index = getIndex(row + rowDelta, column + columnDelta, n);
                             coverBoard[index][hBase] = true;
                         }
                     }
@@ -67,10 +67,10 @@ public class DancingLinksAlgorithm {
     }
 
     private int checkColumnConstraint(boolean[][] coverBoard, int hBase) {
-        for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++) {
+        for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
             for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int r1 = COVER_START_INDEX; r1 <= BOARD_SIZE; r1++) {
+                for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
-                    int index = getIndex(r1, c, n);
+                    int index = getIndex(row, column, n);
                     coverBoard[index][hBase] = true;
                 }
             }
@@ -79,10 +79,10 @@ public class DancingLinksAlgorithm {
     }
 
     private int checkRowConstraint(boolean[][] coverBoard, int hBase) {
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
             for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int c1 = COVER_START_INDEX; c1 <= BOARD_SIZE; c1++) {
+                for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
-                    int index = getIndex(r, c1, n);
+                    int index = getIndex(row, column, n);
                     coverBoard[index][hBase] = true;
                 }
             }
@@ -91,10 +91,10 @@ public class DancingLinksAlgorithm {
     }
 
     private int checkCellConstraint(boolean[][] coverBoard, int hBase) {
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
-            for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++, hBase++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++, hBase++) {
                 for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++) {
-                    int index = getIndex(r, c, n);
+                    int index = getIndex(row, column, n);
                     coverBoard[index][hBase] = true;
                 }
             }
@@ -104,13 +104,13 @@ public class DancingLinksAlgorithm {
 
     private boolean[][] initializeExactCoverBoard(int[][] board) {
         boolean[][] coverBoard = createExactCoverBoard();
-        for (int i = COVER_START_INDEX; i <= BOARD_SIZE; i++) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
-            for (int j = COVER_START_INDEX; j <= BOARD_SIZE; j++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
-                int n = board[i - 1][j - 1];
+                int n = board[row - 1][column - 1];
                 if (n != NO_VALUE) {
                     for (int num = MIN_VALUE; num <= MAX_VALUE; num++) {
                         if (num != n) {
-                            Arrays.fill(coverBoard[getIndex(i, j, num)], false);
+                            Arrays.fill(coverBoard[getIndex(row, column, num)], false);
                         }
                     }
                 }

algorithms/src/main/java/com/baeldung/algorithms/sudoku/DancingNode.java

@@ -4,21 +4,21 @@ class DancingNode {
     DancingNode L, R, U, D;
     ColumnNode C;
 
-    DancingNode hookDown(DancingNode n1) {
+    DancingNode hookDown(DancingNode node) {
-        assert (this.C == n1.C);
+        assert (this.C == node.C);
-        n1.D = this.D;
+        node.D = this.D;
-        n1.D.U = n1;
+        node.D.U = node;
-        n1.U = this;
+        node.U = this;
-        this.D = n1;
+        this.D = node;
-        return n1;
+        return node;
     }
 
-    DancingNode hookRight(DancingNode n1) {
+    DancingNode hookRight(DancingNode node) {
-        n1.R = this.R;
+        node.R = this.R;
-        n1.R.L = n1;
+        node.R.L = node;
-        n1.L = this;
+        node.L = this;
-        this.R = n1;
+        this.R = node;
-        return n1;
+        return node;
     }
 
     void unlinkLR() {

algorithms/src/test/java/algorithms/HillClimbingAlgorithmUnitTest.java

@@ -13,7 +13,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 
-public class HillClimbingAlgorithmTest {
+public class HillClimbingAlgorithmUnitTest {
     private Stack<String> initStack;
     private Stack<String> goalStack;
 

algorithms/src/test/java/algorithms/StringSearchAlgorithmsUnitTest.java

@@ -6,7 +6,7 @@ import org.junit.Test;
 
 import com.baeldung.algorithms.string.search.StringSearchAlgorithms;
 
-public class StringSearchAlgorithmsTest {
+public class StringSearchAlgorithmsUnitTest {
 	
 	
 	@Test

algorithms/src/test/java/algorithms/binarysearch/BinarySearchUnitTest.java

@@ -7,7 +7,7 @@ import org.junit.Assert;
 import org.junit.Test;
 import com.baeldung.algorithms.binarysearch.BinarySearch;
 
-public class BinarySearchTest {
+public class BinarySearchUnitTest {
 
     int[] sortedArray = { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
     int key = 6;

algorithms/src/test/java/algorithms/mcts/MCTSUnitTest.java

@@ -15,7 +15,7 @@ import com.baeldung.algorithms.mcts.tictactoe.Board;
 import com.baeldung.algorithms.mcts.tictactoe.Position;
 import com.baeldung.algorithms.mcts.tree.Tree;
 
-public class MCTSTest {
+public class MCTSUnitTest {
     private Tree gameTree;
     private MonteCarloTreeSearch mcts;
 

algorithms/src/test/java/algorithms/minimax/MinimaxUnitTest.java

@@ -7,7 +7,7 @@ import static org.junit.Assert.*;
 import com.baeldung.algorithms.minimax.MiniMax;
 import com.baeldung.algorithms.minimax.Tree;
 
-public class MinimaxTest {
+public class MinimaxUnitTest {
     private Tree gameTree;
     private MiniMax miniMax;
 

algorithms/src/test/java/com/baeldung/algorithms/bubblesort/BubbleSortUnitTest.java

@@ -4,7 +4,7 @@ import static org.junit.Assert.*;
 
 import org.junit.Test;
 
-public class BubbleSortTest {
+public class BubbleSortUnitTest {
 
     @Test
     public void givenIntegerArray_whenSortedWithBubbleSort_thenGetSortedArray() {

algorithms/src/test/java/com/baeldung/algorithms/editdistance/EditDistanceUnitTest.java

@@ -7,13 +7,13 @@ import org.junit.runners.Parameterized;
 import static org.junit.Assert.assertEquals;
 
 @RunWith(Parameterized.class)
-public class EditDistanceTest extends EditDistanceDataProvider {
+public class EditDistanceUnitTest extends EditDistanceDataProvider {
 
     private String x;
     private String y;
     private int result;
 
-    public EditDistanceTest(String a, String b, int res) {
+    public EditDistanceUnitTest(String a, String b, int res) {
         super();
         x = a;
         y = b;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionBruteForceUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleDetectionBruteForceTest extends CycleDetectionTestBase {
+public class CycleDetectionBruteForceUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleDetectionBruteForceTest(Node<Integer> head, boolean cycleExists) {
+    public CycleDetectionBruteForceUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionByFastAndSlowIteratorsUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleDetectionByFastAndSlowIteratorsTest extends CycleDetectionTestBase {
+public class CycleDetectionByFastAndSlowIteratorsUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleDetectionByFastAndSlowIteratorsTest(Node<Integer> head, boolean cycleExists) {
+    public CycleDetectionByFastAndSlowIteratorsUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionByHashingUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleDetectionByHashingTest extends CycleDetectionTestBase {
+public class CycleDetectionByHashingUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleDetectionByHashingTest(Node<Integer> head, boolean cycleExists) {
+    public CycleDetectionByHashingUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalBruteForceUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleRemovalBruteForceTest extends CycleDetectionTestBase {
+public class CycleRemovalBruteForceUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleRemovalBruteForceTest(Node<Integer> head, boolean cycleExists) {
+    public CycleRemovalBruteForceUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalByCountingLoopNodesUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleRemovalByCountingLoopNodesTest extends CycleDetectionTestBase {
+public class CycleRemovalByCountingLoopNodesUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleRemovalByCountingLoopNodesTest(Node<Integer> head, boolean cycleExists) {
+    public CycleRemovalByCountingLoopNodesUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalWithoutCountingLoopNodesUnitTest.java

@@ -6,11 +6,11 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
 @RunWith(value = Parameterized.class)
-public class CycleRemovalWithoutCountingLoopNodesTest extends CycleDetectionTestBase {
+public class CycleRemovalWithoutCountingLoopNodesUnitTest extends CycleDetectionTestBase {
     boolean cycleExists;
     Node<Integer> head;
 
-    public CycleRemovalWithoutCountingLoopNodesTest(Node<Integer> head, boolean cycleExists) {
+    public CycleRemovalWithoutCountingLoopNodesUnitTest(Node<Integer> head, boolean cycleExists) {
         super();
         this.cycleExists = cycleExists;
         this.head = head;

algorithms/src/test/java/com/baeldung/algorithms/moneywords/NumberWordConverterUnitTest.java

@@ -0,0 +1,84 @@
+package com.baeldung.algorithms.moneywords;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.baeldung.algorithms.numberwordconverter.NumberWordConverter;
+
+public class NumberWordConverterUnitTest {
+
+    @Test
+    public void whenMoneyNegative_thenReturnInvalidInput() {
+        assertEquals(NumberWordConverter.INVALID_INPUT_GIVEN, NumberWordConverter.getMoneyIntoWords(-13));
+    }
+
+    @Test
+    public void whenZeroDollarsGiven_thenReturnEmptyString() {
+        assertEquals("", NumberWordConverter.getMoneyIntoWords(0));
+    }
+
+    @Test
+    public void whenOnlyDollarsGiven_thenReturnWords() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenOnlyCentsGiven_thenReturnWords() {
+        assertEquals("sixty cents", NumberWordConverter.getMoneyIntoWords(0.6));
+    }
+    
+    @Test
+    public void whenAlmostAMillioDollarsGiven_thenReturnWords() {
+        String expectedResult = "nine hundred ninety nine thousand nine hundred ninety nine dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(999_999));
+    }
+    
+    @Test
+    public void whenThirtyMillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "thirty three million three hundred forty eight thousand nine hundred seventy eight dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(33_348_978));
+    }
+    
+    @Test
+    public void whenTwoBillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "two billion one hundred thirty three million two hundred forty seven thousand eight hundred ten dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(2_133_247_810));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWords() {
+        String expectedResult = "nine hundred twenty four dollars and sixty cents";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(924.6));
+    }
+
+    @Test
+    public void whenOneDollarAndNoCents_thenReturnDollarSingular() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenNoDollarsAndOneCent_thenReturnCentSingular() {
+        assertEquals("one cent", NumberWordConverter.getMoneyIntoWords(0.01));
+    }
+
+    @Test
+    public void whenNoDollarsAndTwoCents_thenReturnCentsPlural() {
+        assertEquals("two cents", NumberWordConverter.getMoneyIntoWords(0.02));
+    }
+
+    @Test
+    public void whenNoDollarsAndNinetyNineCents_thenReturnWords() {
+        assertEquals("ninety nine cents", NumberWordConverter.getMoneyIntoWords(0.99));
+    }
+
+    @Test
+    public void whenNoDollarsAndNineFiveNineCents_thenCorrectRounding() {
+        assertEquals("ninety six cents", NumberWordConverter.getMoneyIntoWords(0.959));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWordsVersionTwo() {
+        assertEquals("three hundred ten £ 00/100", NumberWordConverter.getMoneyIntoWords("310"));
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/multiswarm/LolFitnessFunction.java

@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Specific fitness function implementation to solve the League of Legends
+ * problem. This is the problem statement: <br>
+ * <br>
+ * In League of Legends, a player's Effective Health when defending against
+ * physical damage is given by E=H(100+A)/100, where H is health and A is armor.
+ * Health costs 2.5 gold per unit, and Armor costs 18 gold per unit. You have
+ * 3600 gold, and you need to optimize the effectiveness E of your health and
+ * armor to survive as long as possible against the enemy team's attacks. How
+ * much of each should you buy? <br>
+ * <br>
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class LolFitnessFunction implements FitnessFunction {
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * com.baeldung.algorithms.multiswarm.FitnessFunction#getFitness(long[])
+	 */
+	@Override
+	public double getFitness(long[] particlePosition) {
+
+		long health = particlePosition[0];
+		long armor = particlePosition[1];
+
+		// No negatives values accepted.
+		if (health < 0 && armor < 0) {
+			return -(health * armor);
+		} else if (health < 0) {
+			return health;
+		} else if (armor < 0) {
+			return armor;
+		}
+
+		// Checks if the solution is actually feasible provided our gold.
+		double cost = (health * 2.5) + (armor * 18);
+		if (cost > 3600) {
+			return 3600 - cost;
+		} else {
+			// Check how good is the solution.
+			long fitness = (health * (100 + armor)) / 100;
+			return fitness;
+		}
+	}
+
+}

algorithms/src/test/java/com/baeldung/algorithms/multiswarm/MultiswarmUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.algorithms.multiswarm;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+
+import com.baeldung.algorithms.support.MayFailRule;
+
+/**
+ * Test for {@link Multiswarm}.
+ * 
+ * @author Donato Rimenti
+ * 
+ */
+public class MultiswarmUnitTest {
+
+	/**
+	 * Rule for handling expected failures. We use this since this test may
+	 * actually fail due to bad luck in the random generation.
+	 */
+	@Rule
+	public MayFailRule mayFailRule = new MayFailRule();
+
+	/**
+	 * Tests the multiswarm algorithm with a generic problem. The problem is the
+	 * following: <br>
+	 * <br>
+	 * In League of Legends, a player's Effective Health when defending against
+	 * physical damage is given by E=H(100+A)/100, where H is health and A is
+	 * armor. Health costs 2.5 gold per unit, and Armor costs 18 gold per unit.
+	 * You have 3600 gold, and you need to optimize the effectiveness E of your
+	 * health and armor to survive as long as possible against the enemy team's
+	 * attacks. How much of each should you buy? <br>
+	 * <br>
+	 * The solution is H = 1080, A = 50 for a total fitness of 1620. Tested with
+	 * 50 swarms each with 1000 particles.
+	 */
+	@Test
+	public void givenMultiswarm_whenThousandIteration_thenSolutionFound() {
+		Multiswarm multiswarm = new Multiswarm(50, 1000, new LolFitnessFunction());
+
+		// Iterates 1000 times through the main loop and prints the result.
+		for (int i = 0; i < 1000; i++) {
+			multiswarm.mainLoop();
+		}
+
+		System.out.println("Best fitness found: " + multiswarm.getBestFitness() + "[" + multiswarm.getBestPosition()[0]
+				+ "," + multiswarm.getBestPosition()[1] + "]");
+		Assert.assertEquals(1080, multiswarm.getBestPosition()[0]);
+		Assert.assertEquals(50, multiswarm.getBestPosition()[1]);
+		Assert.assertEquals(1620, (int) multiswarm.getBestFitness());
+	}
+
+}

algorithms/src/test/java/com/baeldung/algorithms/pairsaddupnumber/DifferentPairsUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.algorithms.pairsaddupnumber;
+
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+public class DifferentPairsUnitTest {
+
+    /* All different pairs */
+
+    @Test
+    public void whenTraditionalLoop_thenReturnAllDifferentPairs() {
+        /* Data */
+        final int[] input = {2, 4, 3, 3, 8};
+        final int sum = 6;
+        /* Call service */
+        final List<Integer> pairs = DifferentPairs.findPairsWithForLoop(input, sum);
+        /* Check results */
+        assertThat(pairs).hasSize(2).contains(4,3).doesNotContain(8);
+    }
+
+    @Test
+    public void whenStreamApi_thenReturnAllDifferentPairs() {
+        /* Data */
+        final int[] input = {2, 4, 3, 3, 8};
+        final int sum = 6;
+        /* Call service */
+        final List<Integer> pairs = DifferentPairs.findPairsWithStreamApi(input, sum);
+        /* Check results */
+        assertNotNull(pairs);
+        assertEquals(pairs.size(),2);
+        assertEquals(pairs.get(0), new Integer(4));
+        assertThat(pairs).hasSize(2).contains(4,3).doesNotContain(8);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/pairsaddupnumber/ExistingPairsUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.pairsaddupnumber;
+
+import org.junit.Test;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+public class ExistingPairsUnitTest {
+
+    /* All existing pairs */
+
+    @Test
+    public void whenTraditionalLoop_thenReturnAllExistingPairs() {
+        /* Data */
+        final int[] input = {2, 4, 3, 3, 8};
+        final int sum = 6;
+        /* Call service */
+        final List<Integer> pairs = ExistingPairs.findPairsWithForLoop(input, sum);
+        /* Check results */
+        assertThat(pairs).hasSize(4).contains(2,4,3,3).doesNotContain(8);
+    }
+
+    @Test
+    public void whenStreamApi_thenReturnAllExistingPairs() {
+        /* Data */
+        final int[] input = {2, 4, 3, 3, 8};
+        final int sum = 6;
+        /* Call service */
+        final List<Integer> pairs = ExistingPairs.findPairsWithStreamApi(input, sum);
+        /* Check results */
+        assertThat(pairs).hasSize(4).contains(2,4,3,3).doesNotContain(8);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/prime/PrimeGeneratorUnitTest.java

@@ -7,7 +7,7 @@ import java.util.List;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
-public class PrimeGeneratorTest {
+public class PrimeGeneratorUnitTest {
     @Test
     public void whenBruteForced_returnsSuccessfully() {
         final List<Integer> primeNumbers = primeNumbersBruteForce(20);

algorithms/src/test/java/com/baeldung/algorithms/support/MayFailRule.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.support;
+
+import org.junit.Rule;
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * JUnit custom rule for managing tests that may fail due to heuristics or
+ * randomness. In order to use this, just instantiate this object as a public
+ * field inside the test class and annotate it with {@link Rule}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class MayFailRule implements TestRule {
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see org.junit.rules.TestRule#apply(org.junit.runners.model.Statement,
+	 * org.junit.runner.Description)
+	 */
+	@Override
+	public Statement apply(Statement base, Description description) {
+		return new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				try {
+					base.evaluate();
+				} catch (Throwable e) {
+					// Ignore the exception since we expect this.
+				}
+			}
+		};
+	}
+
+}

algorithms/src/test/java/com/baeldung/jgrapht/CompleteGraphUnitTest.java

@@ -12,7 +12,7 @@ import org.jgrapht.graph.SimpleWeightedGraph;
 import org.junit.Before;
 import org.junit.Test;
 
-public class CompleteGraphTest {
+public class CompleteGraphUnitTest {
 
     static SimpleWeightedGraph<String, DefaultEdge> completeGraph;
     static int size = 10;

algorithms/src/test/java/com/baeldung/jgrapht/DirectedGraphUnitTest.java

@@ -24,7 +24,7 @@ import org.jgrapht.traverse.DepthFirstIterator;
 import org.junit.Before;
 import org.junit.Test;
 
-public class DirectedGraphTests {
+public class DirectedGraphUnitTest {
     DirectedGraph<String, DefaultEdge> directedGraph;
 
     @Before

algorithms/src/test/java/com/baeldung/jgrapht/EulerianCircuitUnitTest.java

@@ -12,7 +12,7 @@ import org.jgrapht.graph.SimpleWeightedGraph;
 import org.junit.Before;
 import org.junit.Test;
 
-public class EulerianCircuitTest {
+public class EulerianCircuitUnitTest {
     SimpleWeightedGraph<String, DefaultEdge> simpleGraph;
 
     @Before

animal-sniffer-mvn-plugin/pom.xml

@@ -8,37 +8,32 @@
     <name>example-animal-sniffer-mvn-plugin</name>
     <url>http://maven.apache.org</url>
 
-  <properties>
+    <parent>
-        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>	
+        <groupId>com.baeldung</groupId>
-    </properties>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
 
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-      <version>3.8.1</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
+
     <build>
         <plugins>
-				 <plugin>
-				  <artifactId>maven-compiler-plugin</artifactId>
-				  <version>3.7.0</version>
-				  <configuration>
-					<source>1.8</source>
-					<target>1.8</target>
-				  </configuration>
-				</plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>animal-sniffer-maven-plugin</artifactId>
-					<version>1.16</version>
+                <version>${animal-sniffer-maven-plugin.version}</version>
                 <configuration>
                     <signature>
                         <groupId>org.codehaus.mojo.signature</groupId>
                         <artifactId>java16</artifactId>
-							<version>1.0</version>
+                        <version>${org.codehaus.mojo.signature.java16.version}</version>
                     </signature>
                 </configuration>
                 <executions>
@@ -52,6 +47,10 @@
                 </executions>
             </plugin>
         </plugins>
-
     </build>
+
+    <properties>
+        <animal-sniffer-maven-plugin.version>1.16</animal-sniffer-maven-plugin.version>
+        <org.codehaus.mojo.signature.java16.version>1.0</org.codehaus.mojo.signature.java16.version>
+    </properties>
 </project>

annotations/annotation-processing/pom.xml

@@ -3,6 +3,7 @@
          xmlns="http://maven.apache.org/POM/4.0.0"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
+    <artifactId>annotation-processing</artifactId>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -11,40 +12,17 @@
         <relativePath>../</relativePath>
     </parent>
 
-    <artifactId>annotation-processing</artifactId>
-
-    <properties>
-        <auto-service.version>1.0-rc2</auto-service.version>
-        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
-    </properties>
-
     <dependencies>
-
         <dependency>
             <groupId>com.google.auto.service</groupId>
             <artifactId>auto-service</artifactId>
             <version>${auto-service.version}</version>
             <scope>provided</scope>
         </dependency>
-
     </dependencies>
 
-    <build>
+    <properties>
-
+        <auto-service.version>1.0-rc2</auto-service.version>
-        <plugins>
+    </properties>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <version>${maven-compiler-plugin.version}</version>
-                <configuration>
-                    <source>1.8</source>
-                    <target>1.8</target>
-                </configuration>
-            </plugin>
-
-        </plugins>
-
-    </build>
 
 </project>

annotations/annotation-user/pom.xml

@@ -2,6 +2,7 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
+    <artifactId>annotation-user</artifactId>
 
     <parent>
         <artifactId>annotations</artifactId>
@@ -10,16 +11,12 @@
         <relativePath>../</relativePath>
     </parent>
 
-    <artifactId>annotation-user</artifactId>
-
     <dependencies>
-
         <dependency>
             <groupId>com.baeldung</groupId>
             <artifactId>annotation-processing</artifactId>
             <version>${project.parent.version}</version>
         </dependency>
-
     </dependencies>
 
 </project>

annotations/pom.xml

@@ -1,15 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>annotations</artifactId>
+    <packaging>pom</packaging>
+
     <parent>
         <artifactId>parent-modules</artifactId>
         <groupId>com.baeldung</groupId>
         <version>1.0.0-SNAPSHOT</version>
     </parent>
-    <modelVersion>4.0.0</modelVersion>
-
-    <artifactId>annotations</artifactId>
-    <packaging>pom</packaging>
 
     <modules>
         <module>annotation-processing</module>

apache-bval/pom.xml

@@ -10,6 +10,7 @@
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
     </parent>
+
     <dependencies>
         <dependency>
             <groupId>org.apache.bval</groupId>
@@ -19,7 +20,7 @@
         <dependency>
             <groupId>javax.validation</groupId>
             <artifactId>validation-api</artifactId>
-			<version>1.1.0.Final</version>
+            <version>${javax.validation.validation-api.version}</version>
         </dependency>
         <dependency>
             <groupId>org.apache.bval</groupId>
@@ -30,5 +31,7 @@
 
     <properties>
         <bval.version>1.1.2</bval.version>
+        <javax.validation.validation-api.version>1.1.0.Final</javax.validation.validation-api.version>
     </properties>
+
 </project>

apache-cayenne/pom.xml

@@ -6,7 +6,6 @@
     <artifactId>apache-cayenne</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
-
     <name>apache-cayenne</name>
     <description>Introduction to Apache Cayenne</description>
 
@@ -16,15 +15,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-	<properties>
-		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-		<java.version>1.8</java.version>
-		<mysql.connector.version>5.1.44</mysql.connector.version>
-		<cayenne.version>4.0.M5</cayenne.version>
-		<junit.version>4.12</junit.version>
-	</properties>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.cayenne</groupId>
@@ -56,4 +46,13 @@
         </plugins>
     </build>
 
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+        <mysql.connector.version>5.1.44</mysql.connector.version>
+        <cayenne.version>4.0.M5</cayenne.version>
+        <junit.version>4.12</junit.version>
+    </properties>
+
 </project>

apache-cayenne/src/test/java/com/baeldung/apachecayenne/CayenneAdvancedOperationLiveTest.java

@@ -19,7 +19,7 @@ import java.util.List;
 import static junit.framework.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
-public class CayenneAdvancedOperationTests {
+public class CayenneAdvancedOperationLiveTest {
     private static ObjectContext context = null;
 
     @BeforeClass

apache-cayenne/src/test/java/com/baeldung/apachecayenne/CayenneOperationLiveTest.java

@@ -16,7 +16,7 @@ import static junit.framework.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 
 
-public class CayenneOperationTests {
+public class CayenneOperationLiveTest {
     private static ObjectContext context = null;
 
     @BeforeClass

apache-curator/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Introduction to Apache Curator](http://www.baeldung.com/apache-curator)

apache-curator/pom.xml

@@ -0,0 +1,67 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>apache-curator</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- curator -->
+        <dependency>
+            <groupId>org.apache.curator</groupId>
+            <artifactId>curator-x-async</artifactId>
+            <version>${curator.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.apache.zookeeper</groupId>
+                    <artifactId>zookeeper</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.curator</groupId>
+            <artifactId>curator-recipes</artifactId>
+            <version>${curator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.zookeeper</groupId>
+            <artifactId>zookeeper</artifactId>
+            <version>${zookeeper.version}</version>
+        </dependency>
+        <!-- utils -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson-databind.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.jayway.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${avaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <curator.version>4.0.1</curator.version>
+        <zookeeper.version>3.4.11</zookeeper.version>
+        <jackson-databind.version>2.9.4</jackson-databind.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <avaitility.version>1.7.0</avaitility.version>
+    </properties>
+
+</project>

apache-curator/src/main/java/com/baeldung/apache/curator/modeled/HostConfig.java

@@ -0,0 +1,31 @@
+package com.baeldung.apache.curator.modeled;
+
+public class HostConfig {
+    private String hostname;
+    private int port;
+
+    public HostConfig() {
+
+    }
+
+    public HostConfig(String hostname, int port) {
+        this.hostname = hostname;
+        this.port = port;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setPort(int port) {
+        this.port = port;
+    }
+
+    public String getHostname() {
+        return hostname;
+    }
+
+    public void setHostname(String hostname) {
+        this.hostname = hostname;
+    }
+}

apache-curator/src/test/java/com/baeldung/apache/curator/BaseManualTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.apache.curator;
+
+import org.apache.curator.RetryPolicy;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.retry.RetryNTimes;
+import org.junit.Before;
+
+public abstract class BaseManualTest {
+
+    @Before
+    public void setup() {
+        org.apache.log4j.BasicConfigurator.configure();
+    }
+
+    protected CuratorFramework newClient() {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries, sleepMsBetweenRetries);
+        return CuratorFrameworkFactory.newClient("127.0.0.1:2181", retryPolicy);
+    }
+}

apache-curator/src/test/java/com/baeldung/apache/curator/configuration/ConfigurationManagementManualTest.java

@@ -0,0 +1,89 @@
+package com.baeldung.apache.curator.configuration;
+
+import static com.jayway.awaitility.Awaitility.await;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseManualTest;
+
+public class ConfigurationManagementManualTest extends BaseManualTest {
+
+    private static final String KEY_FORMAT = "/%s";
+
+    @Test
+    public void givenPath_whenCreateKey_thenValueIsStored() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            String key = getKey();
+            String expected = "my_value";
+
+            // Create key nodes structure
+            client.create()
+                .forPath(key);
+
+            // Set data value for our key
+            async.setData()
+                .forPath(key, expected.getBytes());
+
+            // Get data value
+            AtomicBoolean isEquals = new AtomicBoolean();
+            async.getData()
+                .forPath(key)
+                .thenAccept(
+                    data -> isEquals.set(new String(data).equals(expected)));
+
+            await().until(() -> assertThat(isEquals.get()).isTrue());
+        }
+    }
+
+    @Test
+    public void givenPath_whenWatchAKeyAndStoreAValue_thenWatcherIsTriggered()
+        throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            String key = getKey();
+            String expected = "my_value";
+
+            // Create key structure
+            async.create()
+                .forPath(key);
+
+            List<String> changes = new ArrayList<>();
+
+            // Watch data value
+            async.watched()
+                .getData()
+                .forPath(key)
+                .event()
+                .thenAccept(watchedEvent -> {
+                    try {
+                        changes.add(new String(client.getData()
+                            .forPath(watchedEvent.getPath())));
+                    } catch (Exception e) {
+                        // fail ...
+                    }
+                });
+
+            // Set data value for our key
+            async.setData()
+                .forPath(key, expected.getBytes());
+
+            await().until(() -> assertThat(changes.size() > 0).isTrue());
+        }
+    }
+
+    private String getKey() {
+        return String.format(KEY_FORMAT, UUID.randomUUID()
+            .toString());
+    }
+}

apache-curator/src/test/java/com/baeldung/apache/curator/connection/ConnectionManagementManualTest.java

@@ -0,0 +1,79 @@
+package com.baeldung.apache.curator.connection;
+
+import static com.jayway.awaitility.Awaitility.await;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.curator.RetryPolicy;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.retry.RetryNTimes;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.junit.Test;
+
+public class ConnectionManagementManualTest {
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnection_thenClientIsOpened()
+        throws Exception {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+
+            assertThat(client.checkExists()
+                .forPath("/")).isNotNull();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnectionUsingAsyncNotBlocking_thenClientIsOpened()
+        throws InterruptedException {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+
+            AtomicBoolean exists = new AtomicBoolean(false);
+
+            async.checkExists()
+                .forPath("/")
+                .thenAcceptAsync(s -> exists.set(s != null));
+
+            await().until(() -> assertThat(exists.get()).isTrue());
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnectionUsingAsyncBlocking_thenClientIsOpened()
+        throws InterruptedException {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+
+            AtomicBoolean exists = new AtomicBoolean(false);
+
+            async.checkExists()
+                .forPath("/")
+                .thenAccept(s -> exists.set(s != null));
+
+            await().until(() -> assertThat(exists.get()).isTrue());
+        }
+    }
+}

apache-curator/src/test/java/com/baeldung/apache/curator/modeled/ModelTypedExamplesManualTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.apache.curator.modeled;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.apache.curator.x.async.modeled.JacksonModelSerializer;
+import org.apache.curator.x.async.modeled.ModelSpec;
+import org.apache.curator.x.async.modeled.ModeledFramework;
+import org.apache.curator.x.async.modeled.ZPath;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseManualTest;
+
+public class ModelTypedExamplesManualTest extends BaseManualTest {
+
+    @Test
+    public void givenPath_whenStoreAModel_thenNodesAreCreated()
+        throws InterruptedException {
+
+        ModelSpec<HostConfig> mySpec = ModelSpec
+            .builder(ZPath.parseWithIds("/config/dev"),
+                JacksonModelSerializer.build(HostConfig.class))
+            .build();
+
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            ModeledFramework<HostConfig> modeledClient = ModeledFramework
+                .wrap(async, mySpec);
+
+            modeledClient.set(new HostConfig("host-name", 8080));
+
+            modeledClient.read()
+                .whenComplete((value, e) -> {
+                    if (e != null) {
+                        fail("Cannot read host config", e);
+                    } else {
+                        assertThat(value).isNotNull();
+                        assertThat(value.getHostname()).isEqualTo("host-name");
+                        assertThat(value.getPort()).isEqualTo(8080);
+                    }
+
+                });
+        }
+
+    }
+}

apache-curator/src/test/java/com/baeldung/apache/curator/recipes/RecipesManualTest.java

@@ -0,0 +1,74 @@
+package com.baeldung.apache.curator.recipes;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.recipes.leader.LeaderSelector;
+import org.apache.curator.framework.recipes.leader.LeaderSelectorListener;
+import org.apache.curator.framework.recipes.locks.InterProcessSemaphoreMutex;
+import org.apache.curator.framework.recipes.shared.SharedCount;
+import org.apache.curator.framework.state.ConnectionState;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseManualTest;
+
+public class RecipesManualTest extends BaseManualTest {
+
+    @Test
+    public void givenRunningZookeeper_whenUsingLeaderElection_thenNoErrors() {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            LeaderSelector leaderSelector = new LeaderSelector(client, "/mutex/select/leader/for/job/A", new LeaderSelectorListener() {
+
+                @Override
+                public void stateChanged(CuratorFramework client, ConnectionState newState) {
+
+                }
+
+                @Override
+                public void takeLeadership(CuratorFramework client) throws Exception {
+                    // I'm the leader of the job A !
+                }
+
+            });
+
+            leaderSelector.start();
+
+            // Wait until the job A is done among all the members
+
+            leaderSelector.close();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenUsingSharedLock_thenNoErrors() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            InterProcessSemaphoreMutex sharedLock = new InterProcessSemaphoreMutex(client, "/mutex/process/A");
+
+            sharedLock.acquire();
+
+            // Do process A
+
+            sharedLock.release();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenUsingSharedCounter_thenCounterIsIncrement() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+
+            try (SharedCount counter = new SharedCount(client, "/counters/A", 0)) {
+                counter.start();
+
+                counter.setCount(0);
+                counter.setCount(counter.getCount() + 1);
+
+                assertThat(counter.getCount()).isEqualTo(1);
+            }
+
+        }
+    }
+
+}

apache-cxf/cxf-aegis/pom.xml

@@ -2,14 +2,13 @@
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>cxf-aegis</artifactId>
+
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>apache-cxf</artifactId>
         <version>0.0.1-SNAPSHOT</version>
     </parent>
-    <properties>
+
-        <cxf.version>3.1.8</cxf.version>
-    </properties>
     <dependencies>
         <dependency>
             <groupId>org.apache.cxf</groupId>
@@ -17,4 +16,9 @@
             <version>${cxf.version}</version>
         </dependency>
     </dependencies>
+
+    <properties>
+        <cxf.version>3.1.8</cxf.version>
+    </properties>
+
 </project>

apache-cxf/cxf-introduction/pom.xml

@@ -11,32 +11,6 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <cxf.version>3.1.8</cxf.version>
-        <surefire.version>2.19.1</surefire.version>
-    </properties>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <configuration>
-                    <mainClass>com.baeldung.cxf.introduction.Server</mainClass>
-                </configuration>
-            </plugin>
-            <plugin>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>${surefire.version}</version>
-                <configuration>
-                    <excludes>
-                        <exclude>**/*LiveTest.java</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.cxf</groupId>
@@ -50,4 +24,21 @@
         </dependency>
     </dependencies>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <configuration>
+                    <mainClass>com.baeldung.cxf.introduction.Server</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <cxf.version>3.1.8</cxf.version>
+        <surefire.version>2.19.1</surefire.version>
+    </properties>
+
 </project>

apache-cxf/cxf-jaxrs-implementation/pom.xml

@@ -11,34 +11,6 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <cxf.version>3.1.8</cxf.version>
-        <httpclient.version>4.5.2</httpclient.version>
-        <surefire.version>2.19.1</surefire.version>
-    </properties>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <configuration>
-                    <mainClass>com.baeldung.cxf.jaxrs.implementation.RestfulServer</mainClass>
-                </configuration>
-            </plugin>
-            <plugin>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>${surefire.version}</version>
-                <configuration>
-                    <excludes>
-                        <exclude>**/*LiveTest.java</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.cxf</groupId>
@@ -62,4 +34,24 @@
             </exclusions>
         </dependency>
     </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <configuration>
+                    <mainClass>com.baeldung.cxf.jaxrs.implementation.RestfulServer</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <cxf.version>3.1.8</cxf.version>
+        <httpclient.version>4.5.2</httpclient.version>
+        <surefire.version>2.19.1</surefire.version>
+    </properties>
+
 </project>

apache-cxf/cxf-spring/pom.xml

@@ -3,6 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>cxf-spring</artifactId>
     <packaging>war</packaging>
+
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>apache-cxf</artifactId>
@@ -52,15 +53,6 @@
                     <failOnMissingWebXml>false</failOnMissingWebXml>
                 </configuration>
             </plugin>
-            <plugin>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>${surefire.version}</version>
-                <configuration>
-                    <excludes>
-                        <exclude>**/*LiveTest.java</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
         </plugins>
     </build>
 
@@ -102,24 +94,6 @@
                             </execution>
                         </executions>
                     </plugin>
-
-                    <plugin>
-                        <artifactId>maven-surefire-plugin</artifactId>
-                        <version>${surefire.version}</version>
-                        <executions>
-                            <execution>
-                                <phase>integration-test</phase>
-                                <goals>
-                                    <goal>test</goal>
-                                </goals>
-                                <configuration>
-                                    <excludes>
-                                        <exclude>none</exclude>
-                                    </excludes>
-                                </configuration>
-                            </execution>
-                        </executions>
-                    </plugin>
                 </plugins>
             </build>
         </profile>
@@ -130,7 +104,6 @@
         <cxf.version>3.1.8</cxf.version>
         <spring.version>4.3.4.RELEASE</spring.version>
         <javax.servlet-api.version>3.1.0</javax.servlet-api.version>
-
         <maven-war-plugin.version>2.6</maven-war-plugin.version>
         <surefire.version>2.19.1</surefire.version>
         <cargo-maven2-plugin.version>1.6.1</cargo-maven2-plugin.version>

apache-cxf/pom.xml

@@ -19,10 +19,6 @@
         <module>cxf-aegis</module>
     </modules>
 
-    <properties>
-        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
-    </properties>
-
     <build>
         <defaultGoal>install</defaultGoal>
         <pluginManagement>
@@ -35,4 +31,9 @@
             </plugins>
         </pluginManagement>
     </build>
+
+    <properties>
+        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
+    </properties>
+
 </project>

apache-fop/pom.xml

@@ -4,7 +4,6 @@
     <groupId>com.baeldung</groupId>
     <artifactId>apache-fop</artifactId>
     <version>0.1-SNAPSHOT</version>
-
     <name>apache-fop</name>
 
     <parent>
@@ -61,7 +60,7 @@
         <dependency>
             <groupId>org.dbdoclet</groupId>
             <artifactId>herold</artifactId>
-            <version>8.0.4</version>
+            <version>${org.dbdoclet.herold.version}</version>
         </dependency>
 
         <dependency>
@@ -69,7 +68,6 @@
             <artifactId>jtidy</artifactId>
             <version>${jtidy.version}</version>
         </dependency>
-
     </dependencies>
 
     <build>
@@ -82,47 +80,12 @@
         </resources>
     </build>
 
-    <profiles>
-        <profile>
-            <id>integration</id>
-            <build>
-                <plugins>
-                    <plugin>
-                        <groupId>org.apache.maven.plugins</groupId>
-                        <artifactId>maven-surefire-plugin</artifactId>
-                        <executions>
-                            <execution>
-                                <phase>integration-test</phase>
-                                <goals>
-                                    <goal>test</goal>
-                                </goals>
-                                <configuration>
-                                    <excludes>
-                                        <exclude>**/*ManualTest.java</exclude>
-                                    </excludes>
-                                    <includes>
-                                        <include>**/*IntegrationTest.java</include>
-                                        <exclude>**/*LiveTest.java</exclude>
-                                    </includes>
-                                </configuration>
-                            </execution>
-                        </executions>
-                        <configuration>
-                            <systemPropertyVariables>
-                                <test.mime>json</test.mime>
-                            </systemPropertyVariables>
-                        </configuration>
-                    </plugin>
-                </plugins>
-            </build>
-        </profile>
-    </profiles>
-
     <properties>
         <fop.version>1.1</fop.version>
         <avalon-framework.version>4.3</avalon-framework.version>
         <dbdoclet.version>8.0.2</dbdoclet.version>
         <jtidy.version>r938</jtidy.version>
+        <org.dbdoclet.herold.version>8.0.4</org.dbdoclet.herold.version>
     </properties>
 
 </project>

apache-opennlp/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles
+
+- [Intro to Apache OpenNLP](http://www.baeldung.com/apache-open-nlp)

apache-opennlp/pom.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>apache-opennlp</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.opennlp</groupId>
+            <artifactId>opennlp-tools</artifactId>
+            <version>${org.apache.opennlp.opennlp-tools.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${org.assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <org.assertj.version>3.9.0</org.assertj.version>
+        <org.apache.opennlp.opennlp-tools.version>1.8.4</org.apache.opennlp.opennlp-tools.version>
+    </properties>
+
+</project>

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/ChunkerUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.FileInputStream;
+import java.io.InputStream;
+import opennlp.tools.chunker.ChunkerME;
+import opennlp.tools.chunker.ChunkerModel;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class ChunkerUnitTest {
+
+    @Test
+    public void givenChunkerModel_whenChunk_thenChunksAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("He reckons the current account deficit will narrow to only 8 billion.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+
+        InputStream inputStreamChunker = new FileInputStream("src/main/resources/models/en-chunker.bin");
+        ChunkerModel chunkerModel = new ChunkerModel(inputStreamChunker);
+        ChunkerME chunker = new ChunkerME(chunkerModel);
+        String[] chunks = chunker.chunk(tokens, tags);
+        assertThat(chunks).contains("B-NP", "B-VP", "B-NP", "I-NP", "I-NP", "I-NP", "B-VP", "I-VP", "B-PP", "B-NP", "I-NP", "I-NP", "O");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/LanguageDetectorAndTrainingDataUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.Arrays;
+import opennlp.tools.langdetect.Language;
+import opennlp.tools.langdetect.LanguageDetector;
+import opennlp.tools.langdetect.LanguageDetectorFactory;
+import opennlp.tools.langdetect.LanguageDetectorME;
+import opennlp.tools.langdetect.LanguageDetectorModel;
+import opennlp.tools.langdetect.LanguageDetectorSampleStream;
+import opennlp.tools.util.InputStreamFactory;
+import opennlp.tools.util.MarkableFileInputStreamFactory;
+import opennlp.tools.util.ObjectStream;
+import opennlp.tools.util.PlainTextByLineStream;
+import opennlp.tools.util.TrainingParameters;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.tuple;
+import org.junit.Test;
+
+public class LanguageDetectorAndTrainingDataUnitTest {
+
+    @Test
+    public void givenLanguageDictionary_whenLanguageDetect_thenLanguageIsDetected() throws FileNotFoundException, IOException {
+        InputStreamFactory dataIn = new MarkableFileInputStreamFactory(new File("src/main/resources/models/DoccatSample.txt"));
+        ObjectStream lineStream = new PlainTextByLineStream(dataIn, "UTF-8");
+        LanguageDetectorSampleStream sampleStream = new LanguageDetectorSampleStream(lineStream);
+        TrainingParameters params = new TrainingParameters();
+        params.put(TrainingParameters.ITERATIONS_PARAM, 100);
+        params.put(TrainingParameters.CUTOFF_PARAM, 5);
+        params.put("DataIndexer", "TwoPass");
+        params.put(TrainingParameters.ALGORITHM_PARAM, "NAIVEBAYES");
+
+        LanguageDetectorModel model = LanguageDetectorME.train(sampleStream, params, new LanguageDetectorFactory());
+
+        LanguageDetector ld = new LanguageDetectorME(model);
+        Language[] languages = ld.predictLanguages("estava em uma marcenaria na Rua Bruno");
+        
+        assertThat(Arrays.asList(languages)).extracting("lang", "confidence").contains(tuple("pob", 0.9999999950605625),
+                 tuple("ita", 4.939427661577956E-9), tuple("spa", 9.665954064665144E-15),
+                tuple("fra", 8.250349924885834E-25));
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/LemmetizerUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.lemmatizer.DictionaryLemmatizer;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class LemmetizerUnitTest {
+
+    @Test
+    public void givenEnglishDictionary_whenLemmatize_thenLemmasAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John has a sister named Penny.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+        InputStream dictLemmatizer = getClass().getResourceAsStream("/models/en-lemmatizer.dict");
+        DictionaryLemmatizer lemmatizer = new DictionaryLemmatizer(dictLemmatizer);
+        String[] lemmas = lemmatizer.lemmatize(tokens, tags);
+
+        assertThat(lemmas).contains("O", "have", "a", "sister", "name", "O", "O");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/NamedEntityRecognitionUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import opennlp.tools.namefind.NameFinderME;
+import opennlp.tools.namefind.TokenNameFinderModel;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import opennlp.tools.util.Span;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class NamedEntityRecognitionUnitTest {
+
+    @Test
+    public void givenEnglishPersonModel_whenNER_thenPersonsAreDetected() throws Exception {
+        
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John is 26 years old. His best friend's name is Leonard. He has a sister named Penny.");
+        
+        InputStream inputStreamNameFinder = getClass().getResourceAsStream("/models/en-ner-person.bin");
+        TokenNameFinderModel model = new TokenNameFinderModel(inputStreamNameFinder);
+        NameFinderME nameFinderME = new NameFinderME(model);
+        List<Span> spans = Arrays.asList(nameFinderME.find(tokens));
+        assertThat(spans.toString()).isEqualTo("[[0..1) person, [13..14) person, [20..21) person]");
+        List<String> names = new ArrayList<String>();
+        int k = 0;
+        for (Span s : spans) {
+            names.add("");
+            for (int index = s.getStart(); index < s.getEnd(); index++) {
+                names.set(k, names.get(k) + tokens[index]);
+            }
+            k++;
+        }
+        assertThat(names).contains("John","Leonard","Penny");
+    }
+
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/POSTaggerUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class POSTaggerUnitTest {
+
+    @Test
+    public void givenPOSModel_whenPOSTagging_thenPOSAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John has a sister named Penny.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+        assertThat(tags).contains("NNP", "VBZ", "DT", "NN", "VBN", "NNP", ".");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/SentenceDetectionUnitTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.sentdetect.SentenceDetectorME;
+import opennlp.tools.sentdetect.SentenceModel;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class SentenceDetectionUnitTest {
+
+    @Test
+    public void givenEnglishModel_whenDetect_thenSentencesAreDetected() throws Exception {
+
+        String paragraph = "This is a statement. This is another statement. Now is an abstract word for time, "
+                + "that is always flying. And my email address is google@gmail.com.";
+
+        InputStream is = getClass().getResourceAsStream("/models/en-sent.bin");
+        SentenceModel model = new SentenceModel(is);
+
+        SentenceDetectorME sdetector = new SentenceDetectorME(model);
+
+        String sentences[] = sdetector.sentDetect(paragraph);
+        assertThat(sentences).contains("This is a statement.",
+                "This is another statement.",
+                "Now is an abstract word for time, that is always flying.",
+                "And my email address is google@gmail.com.");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/TokenizerUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import opennlp.tools.tokenize.TokenizerME;
+import opennlp.tools.tokenize.TokenizerModel;
+import opennlp.tools.tokenize.WhitespaceTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class TokenizerUnitTest {
+
+    @Test
+    public void givenEnglishModel_whenTokenize_thenTokensAreDetected() throws Exception {
+        InputStream inputStream = getClass().getResourceAsStream("/models/en-token.bin");
+        TokenizerModel model = new TokenizerModel(inputStream);
+        TokenizerME tokenizer = new TokenizerME(model);
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource", ".");
+    }
+    
+    @Test
+    public void givenWhitespaceTokenizer_whenTokenize_thenTokensAreDetected() throws Exception {
+        WhitespaceTokenizer tokenizer = WhitespaceTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource.");
+    }
+    
+    @Test
+    public void givenSimpleTokenizer_whenTokenize_thenTokensAreDetected() throws Exception {
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource", ".");
+    }
+
+}

apache-poi/README.md

@@ -1,4 +1,4 @@
 ### Relevant Articles:
 - [Microsoft Word Processing in Java with Apache POI](http://www.baeldung.com/java-microsoft-word-with-apache-poi)
 - [Working with Microsoft Excel in Java](http://www.baeldung.com/java-microsoft-excel)
-- [Creating a MS PowerPoint Presentation in Java](https://github.com/eugenp/tutorials/tree/master/apache-poi)
+- [Creating a MS PowerPoint Presentation in Java](http://www.baeldung.com/apache-poi-slideshow)

apache-poi/pom.xml

@@ -11,11 +11,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <poi.version>3.15</poi.version>
-        <jexcel.version>1.0.6</jexcel.version>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.poi</groupId>
@@ -34,4 +29,10 @@
             </exclusions>
         </dependency>
     </dependencies>
+
+    <properties>
+        <poi.version>3.15</poi.version>
+        <jexcel.version>1.0.6</jexcel.version>
+    </properties>
+
 </project>

apache-shiro/pom.xml

@@ -3,7 +3,6 @@
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <groupId>com.baeldung</groupId>
     <artifactId>apache-shiro</artifactId>
     <version>1.0-SNAPSHOT</version>
@@ -11,15 +10,9 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>1.5.2.RELEASE</version>
+        <version>${org.springframework.boot.spring-boot-starter-parent.version}</version>
     </parent>
 
-    <properties>
-        <apache-shiro-core-version>1.4.0</apache-shiro-core-version>
-        <log4j-version>1.2.17</log4j-version>
-        <slf4j-version>1.7.25</slf4j-version>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -57,7 +50,6 @@
             <version>${log4j-version}</version>
             <scope>runtime</scope>
         </dependency>
-
     </dependencies>
 
     <build>
@@ -74,5 +66,11 @@
         </plugins>
     </build>
 
+    <properties>
+        <apache-shiro-core-version>1.4.0</apache-shiro-core-version>
+        <log4j-version>1.2.17</log4j-version>
+        <slf4j-version>1.7.25</slf4j-version>
+        <org.springframework.boot.spring-boot-starter-parent.version>1.5.2.RELEASE</org.springframework.boot.spring-boot-starter-parent.version>
+    </properties>
 
 </project>

apache-solrj/pom.xml

@@ -17,7 +17,12 @@
         <dependency>
             <groupId>org.apache.solr</groupId>
             <artifactId>solr-solrj</artifactId>
-            <version>6.4.0</version>
+            <version>${org.apache.solr.solr-solrj.version}</version>
         </dependency>
     </dependencies>
+
+    <properties>
+        <org.apache.solr.solr-solrj.version>6.4.0</org.apache.solr.solr-solrj.version>
+    </properties>
+
 </project>

apache-spark/pom.xml

@@ -1,44 +1,37 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <groupId>com.baeldung</groupId>
     <artifactId>apache-spark</artifactId>
     <version>1.0-SNAPSHOT</version>
     <packaging>jar</packaging>
-
     <name>apache-spark</name>
     <url>http://maven.apache.org</url>
 
-	<properties>
+    <parent>
-		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <groupId>com.baeldung</groupId>
-	</properties>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
 
     <dependencies>
         <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-core_2.10 -->
         <dependency>
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-core_2.10</artifactId>
-			<version>2.2.0</version>
+            <version>${org.apache.spark.spark-core.version}</version>
         </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-			<version>3.8.1</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
-	<build>
+
-		<plugins>
+    <properties>
-			<plugin>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-				<groupId>org.apache.maven.plugins</groupId>
+        <org.apache.spark.spark-core.version>2.2.0</org.apache.spark.spark-core.version>
-				<artifactId>maven-compiler-plugin</artifactId>
+    </properties>
-				<version>3.7.0</version>
+
-				<configuration>
-					<source>1.8</source>
-					<target>1.8</target>
-				</configuration>
-			</plugin>
-		</plugins>
-	</build>
 </project>

apache-thrift/pom.xml

@@ -12,12 +12,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <java.versin>1.8</java.versin>
-        <thrift.version>0.10.0</thrift.version>
-        <maven-thrift.version>0.1.11</maven-thrift.version>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.thrift</groupId>
@@ -34,7 +28,7 @@
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>
-            <version>1.7.12</version>
+            <version>${org.slf4j.slf4j-simple.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -61,4 +55,11 @@
             </plugin>
         </plugins>
     </build>
+
+    <properties>
+        <thrift.version>0.10.0</thrift.version>
+        <maven-thrift.version>0.1.11</maven-thrift.version>
+        <org.slf4j.slf4j-simple.version>1.7.12</org.slf4j.slf4j-simple.version>
+    </properties>
+
 </project>

apache-tika/README.md

@@ -0,0 +1,3 @@
+## Relevant articles:
+
+- [Content Analysis with Apache Tika](http://www.baeldung.com/apache-tika)

apache-tika/pom.xml

@@ -0,0 +1,26 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-tika</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.tika</groupId>
+            <artifactId>tika-parsers</artifactId>
+            <version>${tika.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <tika.version>1.17</tika.version>
+    </properties>
+
+</project>

apache-tika/src/main/java/com/baeldung/tika/TikaAnalysis.java

@@ -0,0 +1,67 @@
+package com.baeldung.tika;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.tika.Tika;
+import org.apache.tika.detect.DefaultDetector;
+import org.apache.tika.detect.Detector;
+import org.apache.tika.exception.TikaException;
+import org.apache.tika.metadata.Metadata;
+import org.apache.tika.mime.MediaType;
+import org.apache.tika.parser.AutoDetectParser;
+import org.apache.tika.parser.ParseContext;
+import org.apache.tika.parser.Parser;
+import org.apache.tika.sax.BodyContentHandler;
+import org.xml.sax.ContentHandler;
+import org.xml.sax.SAXException;
+
+public class TikaAnalysis {
+    public static String detectDocTypeUsingDetector(InputStream stream) throws IOException {
+        Detector detector = new DefaultDetector();
+        Metadata metadata = new Metadata();
+
+        MediaType mediaType = detector.detect(stream, metadata);
+        return mediaType.toString();
+    }
+
+    public static String detectDocTypeUsingFacade(InputStream stream) throws IOException {
+        Tika tika = new Tika();
+        String mediaType = tika.detect(stream);
+        return mediaType;
+    }
+
+    public static String extractContentUsingParser(InputStream stream) throws IOException, TikaException, SAXException {
+        Parser parser = new AutoDetectParser();
+        ContentHandler handler = new BodyContentHandler();
+        Metadata metadata = new Metadata();
+        ParseContext context = new ParseContext();
+
+        parser.parse(stream, handler, metadata, context);
+        return handler.toString();
+    }
+
+    public static String extractContentUsingFacade(InputStream stream) throws IOException, TikaException {
+        Tika tika = new Tika();
+        String content = tika.parseToString(stream);
+        return content;
+    }
+
+    public static Metadata extractMetadatatUsingParser(InputStream stream) throws IOException, SAXException, TikaException {
+        Parser parser = new AutoDetectParser();
+        ContentHandler handler = new BodyContentHandler();
+        Metadata metadata = new Metadata();
+        ParseContext context = new ParseContext();
+
+        parser.parse(stream, handler, metadata, context);
+        return metadata;
+    }
+
+    public static Metadata extractMetadatatUsingFacade(InputStream stream) throws IOException, TikaException {
+        Tika tika = new Tika();
+        Metadata metadata = new Metadata();
+
+        tika.parse(stream, metadata);
+        return metadata;
+    }
+}

apache-tika/src/test/java/com/baeldung/tika/TikaUnitTest.java

@@ -0,0 +1,79 @@
+package com.baeldung.tika;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.tika.exception.TikaException;
+import org.apache.tika.metadata.Metadata;
+import org.junit.Test;
+import org.xml.sax.SAXException;
+
+public class TikaUnitTest {
+    @Test
+    public void whenUsingDetector_thenDocumentTypeIsReturned() throws IOException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.txt");
+        String mediaType = TikaAnalysis.detectDocTypeUsingDetector(stream);
+
+        assertEquals("application/pdf", mediaType);
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenDocumentTypeIsReturned() throws IOException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.txt");
+        String mediaType = TikaAnalysis.detectDocTypeUsingFacade(stream);
+
+        assertEquals("application/pdf", mediaType);
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingParser_thenContentIsReturned() throws IOException, TikaException, SAXException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.docx");
+        String content = TikaAnalysis.extractContentUsingParser(stream);
+
+        assertThat(content, containsString("Apache Tika - a content analysis toolkit"));
+        assertThat(content, containsString("detects and extracts metadata and text"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenContentIsReturned() throws IOException, TikaException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.docx");
+        String content = TikaAnalysis.extractContentUsingFacade(stream);
+
+        assertThat(content, containsString("Apache Tika - a content analysis toolkit"));
+        assertThat(content, containsString("detects and extracts metadata and text"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingParser_thenMetadataIsReturned() throws IOException, TikaException, SAXException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.xlsx");
+        Metadata metadata = TikaAnalysis.extractMetadatatUsingParser(stream);
+
+        assertEquals("org.apache.tika.parser.DefaultParser", metadata.get("X-Parsed-By"));
+        assertEquals("Microsoft Office User", metadata.get("Author"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenMetadataIsReturned() throws IOException, TikaException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.xlsx");
+        Metadata metadata = TikaAnalysis.extractMetadatatUsingFacade(stream);
+
+        assertEquals("org.apache.tika.parser.DefaultParser", metadata.get("X-Parsed-By"));
+        assertEquals("Microsoft Office User", metadata.get("Author"));
+
+        stream.close();
+    }
+}

apache-velocity/pom.xml

@@ -1,11 +1,9 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
-
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <version>0.1-SNAPSHOT</version>
     <artifactId>apache-velocity</artifactId>
-
     <packaging>war</packaging>
     <name>apache-velocity</name>
 
@@ -15,15 +13,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <jdk.version>1.8</jdk.version>
-        <jstl.version>1.2</jstl.version>
-        <maven-war-plugin.version>2.6</maven-war-plugin.version>
-        <org.apache.httpcomponents.version>4.5.2</org.apache.httpcomponents.version>
-        <velocity-version>1.7</velocity-version>
-        <velocity-tools-version>2.0</velocity-tools-version>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.velocity</groupId>
@@ -48,6 +37,7 @@
             </exclusions>
         </dependency>
     </dependencies>
+
     <build>
         <finalName>apache-velocity</finalName>
         <resources>
@@ -67,4 +57,13 @@
             </plugin>
         </plugins>
     </build>
+
+    <properties>
+        <jstl.version>1.2</jstl.version>
+        <maven-war-plugin.version>2.6</maven-war-plugin.version>
+        <org.apache.httpcomponents.version>4.5.2</org.apache.httpcomponents.version>
+        <velocity-version>1.7</velocity-version>
+        <velocity-tools-version>2.0</velocity-tools-version>
+    </properties>
+
 </project>

apache-zookeeper/README.md

@@ -0,0 +1,3 @@
+## Relevant articles:
+
+- [Getting Started with Java and Zookeeper](http://www.baeldung.com/java-zookeeper)

apache-zookeeper/pom.xml

@@ -0,0 +1,28 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-zookeeper</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.zookeeper</groupId>
+            <artifactId>zookeeper</artifactId>
+            <version>${org.apache.zookeeper.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <org.apache.zookeeper.version>3.4.11</org.apache.zookeeper.version>
+    </properties>
+
+</project>
+

apache-zookeeper/src/main/java/com/baeldung/zookeeper/connection/ZKConnection.java

@@ -0,0 +1,33 @@
+package com.baeldung.zookeeper.connection;
+
+import java.io.IOException;
+import java.util.concurrent.CountDownLatch;
+
+import org.apache.zookeeper.WatchedEvent;
+import org.apache.zookeeper.Watcher;
+import org.apache.zookeeper.Watcher.Event.KeeperState;
+import org.apache.zookeeper.ZooKeeper;
+
+public class ZKConnection {
+    private ZooKeeper zoo;
+    final CountDownLatch connectionLatch = new CountDownLatch(1);
+
+    public ZKConnection() {
+    }
+
+    public ZooKeeper connect(String host) throws IOException, InterruptedException {
+        zoo = new ZooKeeper(host, 2000, new Watcher() {
+            public void process(WatchedEvent we) {
+                if (we.getState() == KeeperState.SyncConnected) {
+                    connectionLatch.countDown();
+                }
+            }
+        });
+        connectionLatch.await();
+        return zoo;
+    }
+
+    public void close() throws InterruptedException {
+        zoo.close();
+    }
+}